High/random idle [Archive] - GrandAmGT.com Forum


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04-19-2005, 08:09 PM
I'm having serious problems with my idle lately. It will pick a random spot to idle at- anywhere from 1000 to 2500. Braking becomes difficult, the car will maintain highway speeds with no throttle, and its just a pain in the ass to have to keep dumping the transmission from 2500rpm.

I've searched and found that it might be the TPS or the idle control, I'd like to narrow it down. Only mod I have is a catback, so its not that. I drive it fairly hard, with about 15 passes down the track, and about 6 of those were using a loaded launch.

If I restart the car while driving, that either fixes the problem or it will just pick a different spot to idle at...like I said, its never consistent, and will pick something between 1000 and 2500. I don't believe its the throttle cables either- those are always tight and held in place correctly each time I check.

Any help?

04-20-2005, 09:21 PM
dude i am havin the same EXACT problem.. i jsut made a thread about mine..........with no throttle..my car acclerates, because of the high idle, mine does about around 2000rpms or more........and stoping sux...ruins the breaks, and my gear shifts are all different

04-27-2005, 02:35 PM

04-27-2005, 02:37 PM
did you buy chance install the Casper TPS Enhancer ?

Even if you didn't...i'll bet it's the TPS alone

04-27-2005, 02:45 PM
I'd deffinately try the MAF as a culprit.

04-27-2005, 02:49 PM
TPS, no doubts. Funny shifting, high idle, TPS is bad. You shouldn't even check anything else till you've ruled out the TPS, which is about 95% likely to be your problem. I don't think the maf will cause idle problems of that nature, it can cause weird idles and some driveability problems, but usually in the case your describing, the TPS is the culprit. Fix it, if you've still got issues, then get it on a scantool before you go parts chasing.

04-27-2005, 02:51 PM
^ yay! ...no one ever agress with my suspicions....lol

04-27-2005, 07:26 PM
Its the TPS i bet like others have said. Posted me about 125 to get it fixed all together.

It sucked shifting into gear while at 3k RPMs

04-27-2005, 08:45 PM
I would look at all the hoses for a vacuum leak.

04-27-2005, 11:08 PM
You can run the car w/ a huge vaccum leak and you won't get an idle like that. You will get rpm holds when slowing down, but the car can compensate for a pretty big vacumn leak w/o the idle going up. I missed the rear valvecover vent hose when putting things back together once, the idle was goofy, but it didn't go high, and that was pretty darn big leak. Just my 2 cents.

04-28-2005, 07:17 AM
It's the TPS. My daughter's did the same thing. Around $40 from Autozone. Three torx bit screws and your done.

10-09-2005, 04:11 PM
sorry to bring a thread back from the dead, but im having this problem and have a casper tps that has been on my car for 2mo now. until this week it never idled high, but now it does. would it be in my best interests to disconnect the casper tps or is this just a tradeoff for having the casper installed?

10-09-2005, 11:17 PM
update, started my car tonight and the idle is back to normal. but im curious if anyone has some ideas. im not gonna dismiss this as a fluke because something was obviously wrong with the throttle or sensor. i dont want somethin to happen down the line thats related. if anybody has more questions on my issue shoot them at me, ill kick out answers asap.

edit: back again this morning when i did a cold start. 14-1500rpms idle.

12-08-2005, 02:57 PM
My car has done this a couple of times now since the cold weather has finally arrived.
The first time I noticed it was on the way to work one morning. I noticed that I was idling about 1900 RPMs. Once I got to work, I stopped and started my car. The idle was normal.
It happened again about 2 weeks after that. I noticed it before I went to far and pulled into a parking lot and restarted. Idle was normal.
About 3 weeks after that, I was stopped at a red light and noticed it idling about 1700 RPMs. Before I could pull over to restart, the idle suddenly dropped to normal and the car was fine.
A few day ago, I went out to warm up my car on one particular cold morning. Started it up and 5 minutes later I went to leave and I notice the engine running fast. I check my RPMs and they are around 2100. I shut it off and restarted, RPMs went to normal.
I have now started watching my idle when I first start the car in the moring. It'll jump up to about 1300 RPMs and then slowly drop down to 1000 RPMs after about 10 seconds. Then when the car gets warm, it'll drop down to the normal 600 RPM range.
This only started when the weather got cold.
Any suggestions?

12-08-2005, 03:20 PM
are you positive its at 1900rpm? because i believe mike jung told me the highest is 1350 (which i later realised was the idle i was really at). iirc its a trade off for starting in the cold, but i could be wrong. ive been having this for weeks and no serious problems developing from it so unless you're reading the rpm's wrong, id guess your car should be fine.

12-09-2005, 08:28 AM
Yes I'm positive. BIG difference between 1350, 1900 and 2100....

12-23-2005, 01:00 PM
Could this possible be a bad Idle Air Control valve?

12-23-2005, 04:52 PM
Just a tip for everyone still dealing with this problem, and not wanting to shift into drive at 1500RPM or w.e your at...turn your key all the way, but not far enought to start it..push in the brake and put it into neutral then start it and as soon as you start it drop it into drive or reverse before the idle gets high, less wear on the tranny.

12-23-2005, 09:58 PM
thats too complicated, ill stick to wearing on the tranny, the problem goes away after you start moving..

01-02-2006, 11:33 AM
Where is the TPS sensor at? i am having the same problem, and need to get it fixed ASAP! it is wearing my breaks out

01-02-2006, 12:03 PM
I replaced my TPS on Friday.
So far the idle seems to be behaving itself. Guess I'll know for sure in a couple of weeks.